Furnace



Aug. 3 1926.

B. M. JOHNSON FURNAGE 1925 2 Sheets-Sheet 1 Filed July 9 Patented Aug. 3, 1926.

UNITED STATES 1594,83? PATENT oFFicE.

BOYD M. JOHNSON, OF METUCHEN, NEW JERSEY, ASSIGNOR T0 THE CARBORUNDUM COMPANY, OF NIAGARA FALLS,

NEW YORK, A CORPORATION OF PENNSYLVANIA.

FURNACE.

Application led July 9, 1925. Serial No. 42,413.

The present invention relates to furnaces for the heat treatment of material, such as metal plates or ceramic ware. Furnaces of this character have heretofore been constructed with a main heating chamber having radiating combustion chambers installed therein adjacent its opposite sides. The walls of these combustion chambers have usually been constructed of silicon carbide on account of its high thermal conductivity and high emissivity. In' order to reduce the amount of direct radiation of heat to the material and to render temperature conditions within the heating chamber more uniform, a shielding wall was provided intermediate each combustion chamber and the space occupied by the material. These shielding walls were constructed of one kind of material, either of fire clay, brick or silicon carbide brick, generally the latter.

It is often desirable however that the heating chamber should receive a greater amount of heat in certain portions than in other portions. This is accomplished by the present invention by providing a composite shielding wall in combination with the radiating combustion chamber, the portion of the Wall Where the greatest amount of heat is desired being made of a highly conducting material, such as silicon carbide, and the portion ing made of a less highly conducting material, such as fire clay brick, or of an insulating material, such as diatomaceous earth, or partly'of one such material and partly of the other. In this way it is possible to get a graduation of effective radlated heat by constructing the wall of these materials from top to bottom, from end to end, or from both ends towards the middle. The conductivity of silicon carbide ybrick is about 7 or 8 times that of fire clay brick, and the conductivity of diatomaceous earth and other insulating brick may be 'as low as one-fourth that of re clay brick.

The invention is illustrated in the accompanyin drawings in connection with a furnace a a ted to heat the'materiah'such as copper p atesgtor example, both by radiation an by circulating t e gases of combustion'throu l1 theheating chamber.

In the rawings:

Figure 1 is a ongitudinal centralsection cf the furnace;

where less heat is desired be' Figure 2 is a 'transverse'secton on the line II-II of Figure 1;

Figure'f is a side elevation of one of the shielding walls employed in the construction shown in Figures 1 and 2; and

Figures 4 and 5 are views similar to Figure 3 showing modified forms of shielding Walls embodying my invention.

The furnace illustrated in Figures 1 and comprises a main heating chamber 2 which may be constructed of re brick in the usual manner. Within this main heating chamber adjacent the opposite Sides thereof are arranged radiating cornbustion chambers 3, the walls of which will preferably be constructed of silicon carbide. YEach combustion chamber is divided iuto an upper half4 and a lower half -by a horizontal partition wall 4: extending from the front end of the chamber nearly to the rear end thereof. The lower half of each chamber` has a burner opening 5 insthe front end thereof through which the fuel and air may be introduced. The top Wall 6 of the upperhalr` of each com bustion chamber has openings 7 therein for the escape of the products of combustion into the heating chamber. The gases of combustion circulate through the heating chamber and pass to flues 8 below and at the sides of the heating chamber, as indicated by the arrows shown in Figure 2.

The material is adapted to be introduced into the heating chamber on a car 9 which is adapted to constitute a movable bottom for the heating chamber although lthe heating chamber might, so far as the present invention is concerned, have a permanent floor.

Interposed between the combustion chambers at each side of the heating chamber and the space occupied by the raterial being heated is a shielding wall 1C This shielding wall may be constructed in its lower portion 11 of a highly conducting material such as silicon carbide, in its intermediate portion 12 of a less highly conducting ma-y terial,such as fire clay brick, and in its upper portion 13 of an yinsulating material, such as insulating brick made of diatomaceous earth and a suitable binder.

In the modified formof shielding wall `shown in Figure 4 the endportions 14 of the Wall are formed of silicon carbide, the` ,y

central portion 15 of the insulating` such as diatomaceous earth, and t tions 16 between the middle portion and the end portions of fire brick.`

In the modified construction shown in Figure 5 the shielding wall has its end portions 17 Aand a connecting lower strip 18 formed of silicon carbide, or a similar highly conducting material. These portions enclose a similar shaped portion` 19 which may be constructed of fire clay brick, vand the latter portion encloses a central portion 20 which may be constructed ofthe insulating material.

The combinations shown in Figures 3, 4 and 5 are merely illustrative of the invention and the invention is not limited to such combinations and arrangements of the different materials. Furthermore the shielding wall may be constructed of any two of the materials. For example, one portion of the wall might be constructed of a highly conductingr material such as silicon carbide and` the remaining portion of an insulating material, such as silocel. 0r, the wall might be constructed of fire clay brick and insulating material.

l claim:

1. A furnace structure having a heating chamber and a combustion chamber, and a refractory wall-interposed between the heating chamber and combustion chamber having zones of different thermal conductivity therein for controlling the rate of heat transfer from the combustion chamber to different parts of the heating chamber.

2. A furnace structure having a heating chamber and a combustion chamber, and a refractory screen interposed between the heating chamber and the combustion chamber having zones thereof comprised of refractories of variant thermal conductivity whereby heat transfer to different portions of the heating chamber may be different.

3. A furnace structure having a heating chffuber and a vcombustion chamber, and a refractory screen interposed between the two having Various portions thereof of refractories of different thermal conductivity than other portions thereof, whereby a gradient in the heat transfer to different portlons of the heating chamber is obtainable.

4. A refractory heat screen for use in furnaces and the like having different portions thereof formed of different refractory materials whereby the rate of heat-transfer therethrough may be different in the different parts thereof.

5. A refractory heat screen for use in furnaces and the like having one portion thereof formed of silicon carbide and another portion thereof formed of a refractory material whose thermal conductivity is materially less than that of silicon carbide.

G. A refractory hea-t screen for use in furnaces and the like having one portion thereof formed of silicon carbide, and having another portion formed of a refractory material whose thermal conductivity is materially less than that of silicon carbide, said screen having still another portion of a refractory material whose properties of thermal conductivity are materially different from that of either of theother ortions.

7. A refractory lheat screen or use in furnaces and the like having a. plurality of zones of refractory materials of different thermal conductivity, at least one of the zones being formed of silicon carbide.

8. A refractory heat screen for use in furnaces and the like having one portion of its area formed of silicon carbide and having another portionl of its area formed of fireclay.

5).'A refractory heat screen for use in furnaces and the like having one portion thereof formed of silicon carbide, having another portion thereof formed of reclay .and having still another portion formed of diatomaceous earth.

10. A heat screen for furnaces andthe like, comprising a refractory wall having different ortions of its area formed of materials ofp different thermal conductivities whereby differential rates of heat transfer exist along thel wall.

In testimony whereof have hereunto set my hand.

BOYD M. JOHNSON. 

